The mechanism and stoichiometry of proton transport by the respiratory chain of heart mitochondria and E. coli will be studied. The dependence of ATP synthesis, H2180-Pi exchange reactions, binding of the F1 inhibitor peptide, and conformational change of F1 on the membrane potential and pH gradient of submitochondrial particles will be measured. The effect of possible permeant acids and bases on proton transport measurements will be studied in liposomes. Proton transport by a simple NADH-CoQ reductase from E. coli will be studied in vesicles and a reconstituted system.